From 42267349db0c92a0e1063bd1d07633a3322dfb07 Mon Sep 17 00:00:00 2001
From: Steve Evans <SteveCEvans@users.noreply.github.com>
Date: Thu, 18 Jan 2024 04:34:22 +0000
Subject: [PATCH] Do not permit MSP on softserial ports as the load on the CPU
 is too great (#13303)

Do not permit MSP or serial RX, or baud rates above 19200 on softserial ports as the load on the CPU is too great
---
 src/main/config/config.c |  2 +-
 src/main/io/serial.c     | 24 ++++++++++++++++++++++--
 src/main/io/serial.h     |  2 +-
 3 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/src/main/config/config.c b/src/main/config/config.c
index beacf8bb88..2c8d06e0f0 100644
--- a/src/main/config/config.c
+++ b/src/main/config/config.c
@@ -229,7 +229,7 @@ static void validateAndFixConfig(void)
     }
 #endif
 
-    if (!isSerialConfigValid(serialConfig())) {
+    if (!isSerialConfigValid(serialConfigMutable())) {
         pgResetFn_serialConfig(serialConfigMutable());
     }
 
diff --git a/src/main/io/serial.c b/src/main/io/serial.c
index 4ed8a98b09..bf7a229f83 100644
--- a/src/main/io/serial.c
+++ b/src/main/io/serial.c
@@ -28,6 +28,7 @@
 
 #include "cli/cli.h"
 
+#include "common/maths.h"
 #include "common/utils.h"
 
 #include "drivers/time.h"
@@ -324,9 +325,8 @@ serialPort_t *findSharedSerialPort(uint16_t functionMask, serialPortFunction_e s
 #define ALL_FUNCTIONS_SHARABLE_WITH_MSP (FUNCTION_BLACKBOX | FUNCTION_VTX_MSP)
 #endif
 
-bool isSerialConfigValid(const serialConfig_t *serialConfigToCheck)
+bool isSerialConfigValid(serialConfig_t *serialConfigToCheck)
 {
-    UNUSED(serialConfigToCheck);
     /*
      * rules:
      * - 1 MSP port minimum, max MSP ports is defined and must be adhered to.
@@ -341,6 +341,19 @@ bool isSerialConfigValid(const serialConfig_t *serialConfigToCheck)
     for (int index = 0; index < SERIAL_PORT_COUNT; index++) {
         const serialPortConfig_t *portConfig = &serialConfigToCheck->portConfigs[index];
 
+#ifdef USE_SOFTSERIAL
+        if ((portConfig->identifier == SERIAL_PORT_SOFTSERIAL1) ||
+            (portConfig->identifier == SERIAL_PORT_SOFTSERIAL2)) {
+            // Ensure MSP or serial RX is not enabled on soft serial ports
+            serialConfigToCheck->portConfigs[index].functionMask &= ~(FUNCTION_MSP | FUNCTION_RX_SERIAL);
+
+            // Ensure that the baud rate on soft serial ports is limited to 19200
+            serialConfigToCheck->portConfigs[index].gps_baudrateIndex = constrain(portConfig->gps_baudrateIndex, BAUD_AUTO, BAUD_19200);
+            serialConfigToCheck->portConfigs[index].blackbox_baudrateIndex = constrain(portConfig->blackbox_baudrateIndex, BAUD_AUTO, BAUD_19200);
+            serialConfigToCheck->portConfigs[index].telemetry_baudrateIndex = constrain(portConfig->telemetry_baudrateIndex, BAUD_AUTO, BAUD_19200);
+        }
+#endif
+
         if (portConfig->functionMask & FUNCTION_MSP) {
             mspPortCount++;
         } else if (portConfig->identifier == SERIAL_PORT_USB_VCP) {
@@ -423,6 +436,13 @@ serialPort_t *openSerialPort(
 
     serialPort_t *serialPort = NULL;
 
+#ifdef USE_SOFTSERIAL
+    if (((identifier == SERIAL_PORT_SOFTSERIAL1) || (identifier == SERIAL_PORT_SOFTSERIAL2)) && (baudRate > 19200)) {
+        // Limit baud rate on soft serial ports
+        baudRate = 19200;
+    }
+#endif
+
     switch (identifier) {
 #ifdef USE_VCP
         case SERIAL_PORT_USB_VCP:
diff --git a/src/main/io/serial.h b/src/main/io/serial.h
index a276545ace..9db0c91ee6 100644
--- a/src/main/io/serial.h
+++ b/src/main/io/serial.h
@@ -157,7 +157,7 @@ void serialInit(bool softserialEnabled, serialPortIdentifier_e serialPortToDisab
 void serialRemovePort(serialPortIdentifier_e identifier);
 uint8_t serialGetAvailablePortCount(void);
 bool serialIsPortAvailable(serialPortIdentifier_e identifier);
-bool isSerialConfigValid(const serialConfig_t *serialConfig);
+bool isSerialConfigValid(serialConfig_t *serialConfig);
 const serialPortConfig_t *serialFindPortConfiguration(serialPortIdentifier_e identifier);
 serialPortConfig_t *serialFindPortConfigurationMutable(serialPortIdentifier_e identifier);
 bool doesConfigurationUsePort(serialPortIdentifier_e portIdentifier);